| From: | Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Jan Wieck <janwieck(at)yahoo(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: tuptoaster.c must *not* use SnapshotAny |
| Date: | 2002-01-18 04:00:21 |
| Message-ID: | 3C479DD5.D05FFD9@tpf.co.jp |
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| Lists: | pgsql-hackers |
Tom Lane wrote:
>
> Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> writes:
>
> > For example is it possible to update a toast
> > chunk partially using SnapshotToast ?
>
> As things stand (with either SnapshotToast or the old SnapshotAny way)
> it is never possible to update an individual toast value, either
> partially or wholly. All you can do is lay down a new toast value (with
> a new identifying OID) and then delete the old one.
>
> But I'm not sure that this is wrong, or fixable. Trying to update part
> of a toasted value is very much like wanting to update part of an
> existing row in-place, which we cannot possibly do.
Bytea seems to be considered as a candidate for BLOB
though I think the entirely new type is preferable.
It seems impossible to implement a functionality like
inv_write using bytea which the current large object
stuff has.
regards,
Hiroshi Inoue
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